1. Field of the Invention
The present invention relates to a wireless access system, and more particularly, to a method and apparatus for transmitting/receiving data by a machine to machine de\\(M2M) device to/from a base station.
2. Related Art
Machine to Machine (M2M) Communication, Machine Type Communication (MTC)
Hereinafter, M2M will be described in brief.
Machine to Machine (M2M) communication implies communication between one electronic apparatus and another electronic apparatus. That is, it implies communication between objects. Although the M2M communication generally implies wired or wireless communication between electronic apparatuses or communication between a human-controlled apparatus and a machine, it may particularly imply communication between one electronic apparatus and another electronic apparatus, that is, wireless communication between machines. In addition, M2M devices used in a cellular network have performance or capability inferior to that of typical devices.
A great number of devices exist in a cell. The devices can be distinguished from each other according to a type, class, service type, etc., of the devices. In particular, when M2M communication (or MTC communication) is considered, the total number of devices may be rapidly increased. The M2M devices may have the following features according to a supported service.
1. A great number of devices in a cell
2. A small data amount
3. Infrequent transmission (it may have periodicity)
4. A limited number of data features
5. Insensitive to latency
6. Having low mobility or being fixed
In order to allocate downlink or uplink resources to M2M devices, a base station needs to know a type of the device. In an M2M system, there may be a greater number of (i.e., about hundreds or thousands of) devices in a cell than those in conventional system (i.e., 802.16e or 802.16m).
If such a great number of devices exist in the cell, an addressing mechanism (i.e., 12-bit STID) used in the conventional system may not be enough to accommodate the greater number of devices.